Percutaneous thrombus extraction device and method

ABSTRACT

A percutaneous thrombus extraction device for removing a thrombus from within a blood vessel includes a flexible outer sheath defining a first passage between a proximal end and a distal end. An inner sheath is movably positionable within the first passage. The inner sheath defines a second passage between a proximal end and a distal end. The inner sheath is moveable in a radial direction between a collapsed configuration and an expanded configuration along a length of the inner sheath defined between the proximal end and the distal end. A catheter is movably positionable within the second passage, and has an expandable body at a distal end portion of the catheter. The expandable body is movable between a collapsed configuration and an expanded configuration.

BACKGROUND

The subject matter described herein relates generally to a devicesuitable for extracting emboli, such as thrombi, from within a bloodvessel and, more particularly, to an extraction device configured forpercutaneous vascular introduction to remove a clot or thromboticmaterial without surgical intervention.

Standard treatment for thrombo-embolic disease or blood clots (e.g.,embolism to the superficial femoral artery (“SFA”) or treatment ofdialysis access thrombosis) includes utilizing a embolectomy catheter,such as a Fogarty catheter including an inflatable balloon near a distaltip of the catheter to facilitate removal of emboli and thrombi (e.g., ablood clot) from within a blood vessel.

In the case of SFA, the patient undergoes general anesthesia in theoperating room, a surgical incision is made and the artery is cut openby the surgeon. The catheter is inserted and pushed across the embolismor thrombus, the balloon is inflated to match a diameter of the arteryand pulled back until the thrombus and the balloon are pulled outside ofthe body through the incision. This procedure requires generalanesthesia and a surgical approach. Thus, the procedure is risky to thepatient and very costly, requiring a hospital stay.

BRIEF DESCRIPTION

In one aspect, a method for removing a thrombus from within a bloodvessel includes introducing an inner sheath through a passage defined inan outer sheath positioned within the blood vessel proximate thethrombus. The outer sheath is extracted from within the blood vessel toexpand the inner sheath in a radial direction along a length of theinner sheath to contact an inner surface of the blood vessel. A catheteris moved through the inner sheath to extend the catheter through thethrombus. An expandable body positioned at a distal end portion of thecatheter is expanded and the catheter is retracted, with the expandablebody expanded, into the inner sheath to retain the thrombus within theinner sheath.

In another aspect, an extraction device for removing a thrombus fromwithin a blood vessel includes a flexible outer sheath defining a firstpassage between a proximal end and a distal end. An inner sheath ismovably positionable within the first passage. The inner sheath definesa second passage between a proximal end and a distal end. The innersheath is moveable in a radial direction between a collapsedconfiguration and an expanded configuration along a length of the innersheath defined between the proximal end and the distal end. A catheteris movably positionable within the second passage. The catheter has anexpandable body at a distal end portion of the catheter that is movablebetween a collapsed configuration and an expanded configuration.

In yet another aspect, a catheter that includes a body portion having adistal end and a proximal end. The body portion defines a passagebetween the distal end and the proximal end. A first expandable body ispositioned at a distal end portion of the catheter that is movablebetween a collapsed configuration and an expanded configuration. Asecond expandable body is positioned at an opposing proximal end portionof the catheter. The passage provides fluid communication between thesecond expandable body and the first expandable body. The secondexpandable body is movable between a collapsed configuration and anexpanded configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a blood vessel with a thrombusoccluding flow of blood through the blood vessel;

FIG. 2 is a schematic sectional view of an extraction device partiallypositioned within the blood vessel;

FIG. 3 is a schematic sectional view of the extraction device shown inFIG. 2 with an inner sheath partially extending from a distal end of anouter sheath and expanded to contact an inner surface of the bloodvessel;

FIG. 4 is a schematic sectional view of the extraction device shown inFIG. 3 with a catheter introduced into the inner sheath and extendingthrough the thrombus;

FIG. 5 is a schematic sectional view of the extraction device shown inFIG. 3 with an expandable body of the catheter retracted into a distalend portion of the inner sheath to facilitate removal of the thrombusfrom within the blood vessel;

FIG. 6 is a schematic sectional view of the blood vessel shown in FIG. 1with the thrombus removed from within the blood vessel;

FIG. 7 is a schematic sectional view of an extraction device with anexpandable body of the catheter sealing a distal end portion of theinner sheath to facilitate removal of the thrombus from within the bloodvessel;

FIG. 8 is a schematic sectional view of an alternative extraction devicewith one or more compression strings configured to close a distal endportion of the inner sheath to facilitate removal of the thrombus fromwithin the blood vessel;

FIG. 9 is a schematic sectional view of an alternative extraction devicewith an inner sheath partially extending from a distal end of an outersheath and expanded to contact an inner surface of the blood vessel;

FIG. 10 is a schematic sectional view of an alternative extractiondevice with a catheter introduced into an inner sheath of the extractiondevice and extending through the thrombus;

FIG. 11 is a schematic side view of an exemplary catheter suitable foruse with the extraction device shown in FIGS. 2-5;

FIG. 12 is a schematic side view of the catheter shown in FIG. 11positioned within a blood vessel having a region with a convergentcross-sectional area;

FIG. 13 is a schematic side view of the catheter shown in FIG. 11positioned within the region with a convergent cross-sectional area; and

FIG. 14 is a schematic side view of the catheter shown in FIG. 11positioned within a blood vessel having a region with a convergentcross-sectional area.

DETAILED DESCRIPTION

The embodiments described herein provide an extraction device that canbe introduced into a blood vessel percutaneously for extracting embolior thrombi from within the blood vessel. The minimally invasivepercutaneous introduction reduces or minimizes trauma to the patientwithout the need for general anesthesia or hospitalization, which leadsto improved patient comfort and safety, as well as major savings to thehealth care system. Although the embodiments have been described hereinwith relation to extracting emboli or thrombi from within a blood vesselin the patient's cardiovascular system, it should be apparent to thoseskilled in the art that the extraction device described herein may besuitable for other extraction procedures, such as removing stones frombiliary tubes, for example.

FIG. 1 is a schematic sectional view of a blood vessel 12 with athrombus 14 occluding flow of blood through blood vessel 12. Referringto FIGS. 2-5, in one embodiment an extraction device 20 is configuredfor removing thrombus 14 from within blood vessel 12. Extraction device20 includes a flexible outer tube or sheath 22 that defines a passage 24between a proximal end (not shown) and an opposing distal end 28, asshown in FIG. 2. Outer sheath 22 is a flexible tube suitable forpercutaneously introduction into a vessel, such as blood vessel 12,using techniques known to those skilled in the art. Outer sheath 22 ismade of a suitable biocompatable material including, without limitation,an elastomer, such as silicone rubber, natural rubber,polyvinylchloride, polyurethane, polyester, polytetrafluoroethylene, andsimilar materials. In certain embodiments, outer sheath 22 is made of acomposite material including an incorporated reinforcement material orstructure to provide desired strength, flexibility, torqueability,and/or durability. The construction of catheter tubes suitable forpercutaneous vascular introduction is well described in medicalreferences.

A flexible inner tube or sheath 32 is movably positionable withinpassage 24 defined along a length of outer sheath 22. In a collapsed orpartially collapsed configuration, inner sheath 32 is freely movablethrough passage 24 defined through outer sheath 22 to position innersheath 32 proximate thrombus 14. Inner sheath 32 has a suitable outerdiameter to facilitate reciprocal movement of inner sheath 32 withinouter sheath 22. Inner sheath 32 defines a passage 34 between a proximalend (not shown) and an opposing distal end 38 of inner sheath 32. Innersheath 32 is moveable or expandable in a radial direction between acollapsed configuration and an expanded configuration substantiallyalong an entire length of inner sheath 32 defined between the proximalend and distal end 38. Unlike conventional expandable sheaths thatexpand only at a distal end portion, inner sheath 32 is expandable alongsubstantially the entire length of inner sheath 32 such that an innercross-sectional area of passage 34 increases along the length of innersheath 32 as inner sheath 32 is expanded. Because the cross-sectionalarea of passage 34 increases along an entire length of inner sheath 32,relatively larger emboli, thrombi, and/or other occluding particles canbe easily removed from within blood vessel 12 utilizing inner sheath 32,as described herein.

Suitable flexible materials for use in constructing inner sheath 32 mayinclude, without limitation, the materials suitable for constructingouter sheath 22 as set forth above. In one embodiment, inner sheath 32is self-expandable in a radial direction from an initial collapsedconfiguration, which facilitates movement or translation of inner sheath32 through outer sheath 22, to the expanded configuration, wherein innersheath 32 has a diameter corresponding to an inner diameter of bloodvessel 12 that is larger than a diameter of inner sheath 32 in thecollapsed configuration. In the expanded configuration, inner sheath 32substantially conforms to the inner surface of blood vessel 12.

In one embodiment, with inner sheath 32 positioned proximate thrombus14, inner sheath 32 expands in a radial direction along a length ofinner sheath 32 to contact the inner surface of blood vessel 12 as outersheath 22 is extracted from within blood vessel 12. In one embodiment,outer sheath 22 is at least partially extracted from within blood vessel12 to allow inner sheath 32 to expand in a radial direction along atleast a portion of the length of inner sheath 32. In a particularembodiment, outer sheath 22 is completely extracted from within bloodvessel 12 and removed through the incision to allow inner sheath 32 toexpand in a radial direction along the entire length of inner sheath 32.As inner sheath 32 extends from distal end 28 of outer sheath 22, innersheath 32 in the expanded configuration contacts the inner surface ofblood vessel 12. In an expanded configuration, a distal end 40 of innersheath 32 is configured to retain thrombus 14 to facilitate removal ofthrombus 14 from within blood vessel 12, as shown in FIG. 5. In certainembodiments, the expansion of inner sheath 32 is reversible, i.e., innersheath 32 is urged from the expanded configuration to a collapsed orpartially collapsed configuration, to facilitate removal of inner sheath32 from within blood vessel 12 to complete the procedure. By urginginner sheath 32 to a collapsed or partially collapsed configurationhaving a smaller diameter, potential injury or trauma to blood vessel 12is reduced or minimized in contrast to conventional sheaths having afixed larger diameter, which may cause the blood vessel to tear as theconventional sheath is inserted into and/or removed from within theblood vessel. In an alternative embodiment, only one sheath, for exampleinner sheath 32, is utilized. In this alternative embodiment, innersheath 32 is self-expandable or expandable using any suitable mechanism,such as a crank or another structural mechanism of the sheath, rotation,heating, or a suitable balloon.

To provide for sufficient expansion of inner sheath 32, at least aportion of inner sheath 32 may be constructed of a suitably resilientmaterial, such as a material having desired shape memory properties. Forexample, inner sheath 32 may be fabricated at least partially fromsuitable materials having shape memory properties including, withoutlimitation, Nitinol and other known shape memory alloys (SMA) havingproperties that develop a shape memory effect (SME), which allows thematerial to return to an initial configuration after a force or heatingprocess applied to the material to shape, stretch, compress and/ordeform the material is removed. In a further embodiment, inner sheath 32may be fabricated from a thermally treated metal alloy (TMA) including,without limitation, nickel titanium, beta titanium, copper nickeltitanium, cobalt chrome, stainless steel, and any combination thereof.In an alternative embodiment, inner sheath 32 is expandable using aballoon and/or another mechanism suitable to facilitate expanding innersheath 32. In a particular embodiment, inner sheath 32 is fabricated atleast partially from a suitable polymeric material, such as apolyurethane material. It should be apparent to those skilled in the artthat inner sheath 32 may be made or fabricated using any suitablebiocompatible material preferably, but not necessarily, having suitableshape memory properties. Further, inner sheath 32 may be made orfabricated using any suitable polymer-coated alloy including, withoutlimitation, a nickel titanium alloy coated with polytetrafluoroethylene(PTFE).

In particular embodiments, inner sheath 32 is made from a mesh materialhaving an outer diameter of about 1 millimeter (mm) to about 30 mm andincluding one or more wires forming the mesh material. In one particularembodiment, inner sheath 32 includes a mesh material of 24-72 wires eachhaving a diameter of about 10 microns to about 100 microns. The wiresmay comprise stainless steel, cobalt chrome, nickel titanium, polyesterfilaments (such as a polymeric expandable monofilament), and suitablecombinations thereof. The wires may also be coated with PTFE orparylene, for example. In this embodiment, the braiding angle is about120 degrees and a distance between wires is about 0.05 mm to about 0.5mm.

In the exemplary embodiment, extraction device 20 includes one or moreradio opaque markers located on inner sheath 32 to indicate whetherdistal end 40 of inner sheath 32 is in a radially expandedconfiguration. In certain embodiments, two or more markers arepositioned about a circumference of inner sheath 32. For example, twomarkers may be positioned about 180 degrees apart along thecircumference of inner sheath 32. As shown, for example, in FIG. 3,extraction device 20 includes a first radio opaque marker 42 located ata first position 44 on a circumferential edge 46 of distal end 38 and asecond radio opaque marker 52 located at a second position 54 oncircumferential edge 46 of distal end 38 opposing first position 44 tofacilitate determining whether distal end 40 of inner sheath 32 is in aradially expanded configuration or a convergent configuration, forexample. When inner sheath 32 is collapsed, first radio opaque marker 42is very close to second radio opaque marker 52, and when inner sheath 32expands a distance between first radio opaque marker 42 and second radioopaque marker 52 increases to allow an operator using fluoroscopy todetermine whether inner sheath 32 is in a collapsed configuration or anexpanded configuration, for example. In an alternative embodiment, theradio opaque marker includes a string positioned about a circumferenceof inner sheath 32. The string is seen as a small circle when innersheath 32 is collapsed and as a relatively larger circle when innersheath 32 expands. As shown in FIG. 3, first position 44 and secondposition 54 are located on a line 60 defining a diameter of inner sheath32 with inner sheath 32 in the radially expanded configuration.

Referring further to FIGS. 4 and 5, in the exemplary embodimentextraction device 20 includes a suitable mechanism, such as a catheter70, a tube, or a wire, movably positionable within passage 34 definedthrough inner sheath 32. In the exemplary embodiment, catheter 70includes a body portion 74 that defines a passage 76 between a proximalend portion (not shown in FIGS. 4 and 5) and an opposing distal endportion 78 of catheter 70. A first expandable body 72 is positioned atdistal end portion 78 of catheter 70. First expandable body 72 ismovable between a radially collapsed configuration and a radiallyexpanded configuration, as shown in FIGS. 4 and 5. In a particularembodiment, first expandable body 72 includes an inflatable balloon 75,as shown in FIGS. 4 and 5, that is inflatable to move from a collapsedor deflated configuration to an inflated configuration. In the inflatedconfiguration, balloon 75 conforms to the inner surface of blood vessel12 to facilitate removing thrombus 14 from within blood vessel 12 andtransferring thrombus 14 into expanded inner sheath 32. Balloon 75 isconstructed of a suitable material including, without limitation,polytetraflouroetylene and polyolefin materials, such as a polyethylenematerial. It should be apparent to those skilled in the art that balloon75 may be made or fabricated using any suitable biocompatible material,the construction of which is well described in medical references.

In an alternative embodiment, first expandable body 72 includes one ormore wire coils or one or more flexible members forming anumbrella-shaped or disc-shaped expandable body (none of which are shown)provided at distal end 78 of catheter 70 that are movable between acollapsed or retracted configuration and a radially expandedconfiguration. With first expandable body 72 in the expandedconfiguration, catheter 70 is translated in a proximal axial directionthrough blood vessel 12 to urge thrombus 14 into inner sheath 32 tofacilitate removing thrombus 14 from within blood vessel 12. FIG. 6 is aschematic sectional view of blood vessel 12 shown in FIG. 1 withthrombus 14 removed from within blood vessel 12. In one embodiment, avessel closure device (not shown) including, for example, a suture or aswelling material, may be operatively coupled to outer sheath 22 orinner sheath 32 so that with thrombus 14 removed from within bloodvessel 12 the incision site in blood vessel 12 can be closed uponremoval of outer sheath 22 and/or inner sheath 32.

In a particular embodiment, as shown in FIG. 7, at least a portion ofinner sheath 32 is made of a suitable mesh material. With thrombus 14positioned within distal end 38 of inner sheath 32, first expandablebody 72 is positioned against inner sheath 32, such as by pullingcatheter 70 in the proximal axial direction, to seal distal end 38 ofinner sheath 32 to facilitate removal of thrombus 14 from within bloodvessel 12. In one embodiment, a suitable negative pressure may beapplied to maintain thrombus 14 positioned within inner sheath 32 tofacilitate removing thrombus 14 from blood vessel 12 and/or to aspiratethe dislodged thrombus 14 into inner sheath 32. Referring further toFIG. 8, one or more compression strings 80 may be positioned about andoperatively coupled to circumferential edge 46 of distal end 38 toprovide closure to distal end portion 40, as desired, to maintainthrombus 14 within inner sheath 32. With thrombus 14 positioned withininner sheath 32, compression string 80 is pulled to urge distal endportion 40 closed and seal distal end 38 of inner sheath 32 tofacilitate removal of thrombus 14 from within blood vessel 12. Inalternative embodiments, other suitable mechanisms including, withoutlimitation, heat, one or more wires, and/or a balloon or anotherexpandable body, may be utilized to seal distal end 38 of inner sheath32 to secure thrombus 14 within inner sheath 32.

FIG. 9 is a schematic sectional view of extraction device 20 with aninner sheath 132 partially extending from a distal end of outer sheath22 and expanded to contact an inner surface of blood vessel 12. In aparticular embodiment, as shown in FIG. 9, at least a portion of innersheath 132 is made of a suitable mesh material including one or moretubes 134. A plurality of apertures 136 are defined through tubes 134 toprovide fluid communication between an inner lumen of tube 132 and bloodvessel 12. A suitable negative pressure, indicated by directional arrows138, may be applied through apertures 136 to maintain thrombus 14 (notshown in FIG. 9) positioned within inner sheath 132 to facilitateremoving thrombus 14 from blood vessel 12 and/or to aspirate thedislodged thrombus 14 into inner sheath 132.

FIG. 10 is a schematic sectional view of extraction device 20 withcatheter 70 introduced into an inner sheath 142 and extending throughthrombus 14. In this embodiment, as shown in FIG. 10, a second innersheath 144 is positioned distally to inner sheath 142. With catheter 70extended through thrombus 14, second inner sheath 144 is expanded tocontact an inner surface of blood vessel 12. In a particular embodiment,inner sheath 142 and/or second inner sheath 144 are made of a suitablemesh material. A plurality of apertures 146 are defined through catheter70 to provide fluid communication between an inner lumen of catheter 70and blood vessel 12. A suitable negative pressure may be applied throughapertures 146 to draw thrombus 14 into inner sheath 142 to facilitateremoving thrombus 14 from blood vessel 12 and/or to aspirate thedislodged thrombus 14 into inner sheath 142.

Referring now to FIGS. 11-14, in the exemplary embodiment, a second orexternal expandable body 82 is positioned at an opposing proximal endportion 84 of catheter 70 that extends outwardly from blood vessel 12and percutaneously through the entry incision external to the patient'sbody. Passage 76 defined through body portion 74 provides fluidcommunication between second expandable body 82 and first expandablebody 72. A suitable liquid or gas, such as carbon dioxide or air, can betransferred between first expandable body 72 and second expandable body82 to expand or collapse expandable body 72, as desired. Secondexpandable body 82 is movable between a collapsed configuration and aradially expanded configuration. In the exemplary embodiment shown inFIGS. 11-14, second expandable body 82 includes an inflatable balloon 85that is inflatable to move from a collapsed or deflated configuration toan inflated configuration. In the exemplary embodiment, second balloon85 is similar in size and configuration to first balloon 75, although inalternative embodiments, second balloon 85 may have different dimensionsand/or a different configuration than the dimensions and/or theconfiguration of first balloon 75.

In the exemplary embodiment, an outer circumference of first expandablebody 72 is adjustable to conform to the inner surface of blood vessel12. Further, first expandable body 72 can be expanded to a specific ordesired shape by inflating first balloon 75. In this embodiment, secondexpandable body 82 is configured to collapse in order to expand firstexpandable body 72. As second expandable body 82 is collapsed, fluid,such as a suitable gas, is transferred from within second expandablebody 82 and/or passage 76 into first expandable body 72 to increase avolume of fluid contained within first expandable body 72 andcorrespondingly increase the outer circumference of first expandablebody 72, as shown in FIG. 14 for example, to conform to the innersurface of blood vessel 12 without damaging the inner surface of bloodvessel 12 or rupturing or tearing the blood vessel wall. Conversely, ifthe volume within first expandable body 72 is decreased, such as bytranslating catheter 70 through a region 90 of blood vessel 12 having adecreasing cross-section area, as shown in FIGS. 12 and 13, fluid fromwithin first expandable body 72 is transferred into passage 76 and/orsecond expandable body 82, thus decreasing the volume of fluid containedwithin first expandable body 72 and increasing a volume of fluidcontained within second expandable body 82.

Referring to FIGS. 1-14, one or more embodiments of a method forremoving a thrombus from within a blood vessel are described herein. Forexample, a method for removing thrombus 14 from within blood vessel 12using extraction device 20 includes introducing inner sheath 32 throughpassage 24 defined in outer sheath 22 positioned within blood vessel 12proximate thrombus 14. Outer sheath 22 is extracted from within bloodvessel 12 to expand inner sheath 32 along a length of inner sheath 32 tocontact an inner surface of blood vessel 12. As outer sheath 22 isextracted from blood vessel 12, inner sheath 32 extends from distal end28 of outer sheath 22 and expands to conform to the inner surface ofblood vessel 12. In the exemplary embodiment, inner sheath 32 expandsalong substantially the entire length of inner sheath 32. In aparticular embodiment, inner sheath 32 self-expands to match an innercircumference of blood vessel 12. As inner sheath 32 expands in a radialdirection, inner sheath 32 contacts the inner surface of blood vessel12.

With outer sheath 22 retracted from within blood vessel 12 and removedpercutaneously through the incision, catheter 70 is introduced intoinner sheath 32 and moved through inner sheath 32 to extend catheter 70through thrombus 14. With at least distal end portion 78 of catheter 70extended through thrombus 14, first expandable body 72 positioned atdistal end portion 78 of catheter 70 is expanded to move firstexpandable body 72 radially outward toward the expanded configuration toconform to the inner surface of blood vessel 12. With an outer surfaceof first expandable body 72 contacting and conforming to the innersurface of blood vessel 12, catheter 70 and expanded first expandablebody 72 are retracted into distal end 38 of inner sheath 32 to retainthrombus 14 within inner sheath 32. Thrombus 14 is then removed fromwithin blood vessel 12.

In a particular embodiment, first expandable body 72 positioned atdistal end portion 78 of catheter 70 includes first inflatable balloon75 positioned at distal end portion 78 of catheter 70. Catheter 70 isthen moved, with first inflatable balloon 75 inflated, into distal end38 of inner sheath 32. With thrombus 14 retained with inner sheath 32,first inflatable balloon 75 may be partially deflated to facilitatetranslating catheter 70 through blood vessel 12 as desired.

In one embodiment, outer sheath 22 is introduced percutaneously intoblood vessel 12 proximate thrombus 14. Inner sheath 32 is then insertedinto outer sheath 22 and inner sheath 32 in a collapsed or partiallycollapsed configuration is moved through outer sheath 22 toward thrombus14. Inner sheath 32 self-expands in a radial direction as inner sheath32 moves relative to outer sheath 22 and exits distal end 28 of outersheath 22.

The above-described extraction device can be introduced into a vessel,such as an occluded blood vessel, percutaneously for extracting embolior thrombi from within the blood vessel. The minimally invasivepercutaneous introduction reduces or minimizes trauma to the patientwithout the need for general anesthesia or hospitalization. In oneembodiment, once the inner sheath has been positioned within the outersheath and proximate the thrombus, the outer sheath can be removed fromwithin the blood vessel to allow the inner sheath to expand in a radialdirection substantially along an entire length of the inner sheath tofacilitate removal of the thrombus from within the blood vessel.Further, the catheter as described herein includes a first expandablebody, such as a first inflatable balloon, positioned distally withrespect to the thrombus and a second expandable body, such as a secondinflatable balloon, positioned external to the incision that cooperateto transfer fluid into or out of the first expandable body to increaseor decrease, respectively, a volume of fluid contained within the firstexpandable body. This transfer of fluid allows the outer circumferenceof the first expandable body to be accurately adjusted to conform to theinner surface of the blood vessel without applying an undesired pressureagainst the blood vessel that may damage the inner surface of the bloodvessel or tear or rupture the blood vessel wall.

Exemplary embodiments of a percutaneous thrombus extraction device andmethods of utilizing the thrombus extraction device for removing embolior thrombi from within a blood vessel are described above in detail. Theextraction device is not limited to the specific embodiments describedherein, but rather, components of the extraction device may be utilizedindependently and separately from other components described herein.Further, the described extraction device can also be defined in, or usedin combination with, other devices and/or methods, and are not limitedto practice with only the extraction device as described herein.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for removing a thrombus from within ablood vessel, said method comprising: introducing an inner sheaththrough a passage defined in an outer sheath positioned within the bloodvessel proximate the thrombus, wherein the inner sheath isself-expandable along substantially an entire length of the innersheath; extracting the outer sheath from within the blood vessel suchthat at least a portion of the inner sheath extends beyond a distal endportion of the outer sheath; self-expanding substantially an entirelength of the portion of the inner sheath extending beyond the distalend portion of the outer sheath in a radial direction to contact aninner surface of the blood vessel, a distal end of the inner sheathpositioned on a proximal side of the thrombus; moving a catheter throughthe inner sheath to extend the catheter through the thrombus; expandingan expandable body positioned at a distal end portion of the cathetersuch that substantially an entire length of the expandable body conformsto the inner surface of the blood vessel, substantially the entirelength of the expandable body positioned on a distal side of thethrombus; and retracting the catheter, with substantially the entirelength of the portion of the inner sheath and substantially the entirelength of the expandable body expanded, into the inner sheath to retainthe thrombus within the inner sheath such that substantially the entirelength of the portion of the inner sheath is in contact with the innersurface of the blood vessel and substantially the entire length of theexpandable body conforms to at least one of the inner surface of theblood vessel and an inner surface of the inner sheath.
 2. The method inaccordance with claim 1, further comprising extracting the thrombus fromwithin the blood vessel.
 3. The method in accordance with claim 1,further comprising introducing the outer sheath into the blood vesselproximate the thrombus wherein self-expanding substantially an entirelength further comprises self-expanding the inner sheath radiallyoutward as the inner sheath exits the outer sheath.
 4. The method inaccordance with claim 3, further comprising extracting the inner sheathand the catheter with the retained thrombus from within the bloodvessel.
 5. The method in accordance with claim 3, wherein the outersheath is introduced into the blood vessel percutaneously.
 6. The methodin accordance with claim 3, wherein the inner sheath moves through theouter sheath in a collapsed configuration.
 7. The method in accordancewith claim 1, wherein expanding the expandable body comprises inflatinga balloon positioned at the distal end portion of the catheter.
 8. Themethod in accordance with claim 7, wherein the catheter is moved withthe balloon inflated into the inner sheath.
 9. The method in accordancewith claim 7, further comprising partially deflating the balloon withthe thrombus retained within the inner sheath.